Electric current rectifier



Feb. 27, 1934. KOBE-L 1,949,104

ELECTRIC CURRENT RECTIFIER Filed May 28, 1931 /n en for frns/ Kobe/ Homey.

Patented Feb. 27, 1934 UNITED STATES PATENT OFFICE ELECTRIC CURRENTRECTIFIER Switzerland Application May 28, 1931, Serial No. 540,665, andin Germany June 6, 1930 6 Claims.

This invention relates to improvements in electric power rectifiers ofthe metallic vapor arc type in which the vapor and the are are inclosedwithin a metallic tank.

An electric power rectifier of the character described must be cooledand the inclosing tank is therefore made double-walled to permit thecirculation of a cooling medium therethrough. The interior surfaces ofthe tank thus provide cooled surfaces on which a portion of the metallicvapor condenses and returns to the cathode which is usually mercury. Inthe normal operation of such rectifiers, the cooling surfaces howevertake on a potential which is positive, by several volts, relative to thecathode. The positive mercury ions are repelled from the cooled surfacesof the tank and the cooled surfaces of a cooling coil, generallyarranged within the tank, by the positive charges thereon which exert anelectrical 2Q damping on the natural movement of the ions resulting fromtheir temperature. Clouds of ions thus checked hinder the fiow of theneutral mercury molecules so that the transmission of heat from thevapor to the condensation surfaces is retarded. The reunion of the ionswith the molecules also prevents condensation of the ions as long as thesame are electrically charged. Both of the above disadvantages may beavoided if the surfaces on which the vapor is to be condensed arecharged negatively relative to the cathode.

It is, therefore, among the objects of the present invention to providean electric power rectifier of the metallic vapor are metal inclosedtype with means for preventing the formation of a layer of ions adjacentbut out of contact with the cooled surfaces of the inclosing tank.

Another object of the invention is to provide an electric powerrectifier of the metallic vapor are metal inclosed type in which theinclosing tank is cooled and the cooled surfaces thereof are chargednegatively with respect to the cathode.

Objects and advantage, other than those above set forth, will beapparent from the following description when read in connection with theaccompanying drawing which somewhat diagrammatically illustrates oneembodiment of the present invention.

Referring more particularly to the drawing by characters of reference,the reference numeral 1 designates a double-walled metallic tank havinga cathode well 2 formed in the bottom thereof to retain a vaporizablecathode material 3 which is preferably mercury. A double-walledextension 4 projects from the cover of the tank in communication withthe interior thereof and forms a condensation chamber or dome for themetallic vapor. A plurality of anodes 6 extend through the tank and areinsulated therefrom by bushings 7.- Both the anodes and the bushings aresealed in gas-tight relation into the tank walls eothrough which theyextend. The anodes are each provided with are guides 8 as is usual inelectric power rectifiers of the metal tank inclosed type.

A cooling coil 11 is arranged within the tank 1 and is supplied with acooling fluid from a suit- 0 able source through an inlet 12 and thecooling fluid discharges from the coil through an outlet 13. Both theinlet and the outlet to the cooling coil pass through the tank wallsthrough insulators 14 sealed in gas-tight relation therewith. 10Although the cooling coil has been shown as oylindrical andsubstantially centered within the rectifier, it will be understood thatit may be shaped differently and may also be arranged in differentpositions within the tank.

A suitable source of potential, such as a battery 16, is shown as beingconnected with the coil 11 at the point 20 and as being connected with aconductor 17 leading from the cathode 3. Potential may be continuouslyapplied to the coil or so the potential may be controlled by a switch18. The switch may be controlled manually or, as shown, may be connectedacross a shunt 19 with the conductor 17 in such manner that a closingcoil 21 closes the switch when the output of the 35 rectifier reaches acertain value. It will be apparent that the switch may also becontrolled in response to voltage, vacuum, vapor pressure in therectifier, temperature of the rectifier, or cooling water temperature inany way now known. The value of the negative potential impressed on thecoil may also be varied automatically in response to any suitable value.

The present invention thus provides means whereby the charging of thecooling surfaces 5 within a rectifier at a potential which is negativewith respect to the cathode causes a fiow of positive mercury ions tosuch surfaces. The path of the neutral molecules to such condensingsurfaces is therefore cleared and the ionized vapor 1 rising from thecathode is carried along by the stream of ions and molecules thusreducing the vapor pressure within the rectifier. An electrical drop isproduced in this manner in addition to the partial pressure drop withinthe tank so that the fiow of the vapor to the cooled walls is increasedand the transfer of heat therefrom is facilitated.

Although but one embodiment of the present invention has beenillustrated and described, it

will be apparent to those skilled in the art that various changes andmodifications may be made therein Without departing from the spirit ofthe invention or from the scope of the appended claims.

The invention claimed is:

In combination with an electric current rectifier comprising a casing, aplurality of anodes and a vaporizable cathode constituting arcingelectrodes for the flow of electric current therebetween, of meansarranged within said casing external to the path for flow of currentbetween said anodes c ode operable to condense material vaporized n saidcathode, and means for impressing upon the first said means electricpotential negative with respect to the potential of said cathode.

2. In combination with an electric current rectifier comprising acasing, a plurality of anodes and a vaporizable cathode constitutingarcing electrodes for the how of current therebetween, of means havingcooled surfaces arranged within said casing external to the path of flowof current between said anodes and cathode operable to condense materialvaporized from said cathode, and means for impressing upon the firstsaid means electric potential negative with respect to the potential ofsaid cathode.

3. In combination with an electric current rectifier comprising a casinghaving cooled surfaces, a plurality of anodes and a vaporizable cathodeconstituting arcing electrodes for the flow of current therebetween, ofmeans arranged within said casing external to the path or" flow ofcurrent between said electrodes and electrically insulated from saidcasing operable to condense material vaporized from said cathode, andmeans for impressing upon the first said means an electrical potentialnegative with respect to the potential impressed upon the said cathode.

4. In combination with an electric current rectifier comprising acasing, a plurality of anodes and a vaporizable cathode constitutingarcing electrodes for the flow of current therebetween, of a coilforming a path for the circulation of a. cooling fluid arranged withinsaid casing external to the paths for the flow of current from saidanodes to said cathode, the said coil being electrically insulated fromsaid casing and being operable to condense material vaporized from saidcathode, and means for impressing upon said coil an electrical potentialnegative with respect to the potentials impressed upon the said cathode.

5. In combination with an electric current rectifier comprising a casinghaving cooled surfaces, a plurality of anodes and a vaporizable cathodeconstituting arcing electrodes for the flow of current therebetween, ofmeans arranged within said casing external to the path for flow ofcurrent between said electrodes and electrically insulated from saidcasing operable to condense material vaporized from said cathode, a.source of electric current supply operable to impress a potential uponsaid means negative with respect to the potential of said cathode, andswitch means operable to efieot operative connectionoof said source ofcurrent supply with the first said means.

6. In combination with an electric current rectifier comprising a casinghaving cooled surfaces, a plurality of anodes and a vaporizable cathodeconstituting arcing electrodes for the flow of current therebetween, or"means arranged within said casing external to the path for the flow ofcurrent between said electrodes and electrically insulated from saidcasing operable to condense material vaporized from said cathode, asource of electric current supply operable to impress a potential uponsaid means negative with respect to the potential of the said cathode,and switch means actuated responsive to and in dependence upon themagnitude of the current flowing between said electrodes for causingoperative connection of said source of current supply with the firstsaid means.

ERNST KOBEL.

